This invention relates to an electric generator system for an automobile, and particularly to an electric power supply system for use in an automobile having loads which require higher voltages than the normal battery voltages
As such a high voltage load in the present automobile field, there is known the deicing heater for the automobile's windshield Since the deicing heater needs a high electric power, the power supply voltage must be high. Heating systems for melting the ice stuck to the automobile's windshield glass in a short time are proposed in U.S. Pat. No. 4,084,126 granted to Clements and issued on Apr. 11, 1978, and in U.S. Pat. No. 4,668,270 granted to Ramus and issued on May 6, 1987. In addition, power supplies for vehicles which generate high voltages re disclosed in JP-A-63-9500 filed by General Motors Corporation with priority based on U.S. patent application Ser. Nos. 897,023 (now abandoned) and 50,999 (now U.S. Pat. No. 4,780,619) filed on Aug. 15, 1986 and on May 15, 1987, respectively. In these power supplies for heaters, a voltage is generated by an AC generator and rectified into the normal DC rated voltage In addition to the rated voltage, for obtaining a high voltage a field current is increased to increase the output voltage from the generator or the rated voltage is boosted by a transformer. The various equipments for automobiles are mounted to be in positions easy for repair and maintenance, and there may be an opportunity to be damaged by a traffic accident or the like. Therefore, even by either approach for high voltage, a highly reliable power supply must be produced which is capable of preventing short-circuiting accidents, and has no adverse effect on the other low-voltage circuits even under the operation of the high-voltage circuit.
Accordingly, it is an object of this invention to provide a high-reliability power supply for vehicles which is capable of maintaining the high-voltage circuit safe and simultaneously supplying power to both a high-voltage circuit and a low-voltage circuit.